Glass forming ability and microstructure of hard magnetic Nd60Al20Fe20 glass forming alloy

Glass forming ability (GFA), magnetic properties and microstructure of Nd60Al20Fe20 as-cast rod were investigated and further compared with Nd60Al10Fe30 glass forming alloy. The rod prepared by suction casting with a diameter of 3 mm exhibits the typical amorphous nature in XRD pattern, distinct glass transition in DSC traces and hard magnetic properties. It is found that the diameter of cast Nd60Al20Fe20 glassy rod is much larger than the critical section thickness (Zc) of bulk metallic glass (BMG) predicted from DSC measurements. A few nano-crystalline particles with the structure and composition similar to Ax phase in Nd-Fe alloys were found embedded randomly in amorphous matrix and could be the origin of hard magnetic properties of the as-cast rods. The GFA of the alloy appears to be enhanced by the precipitation of metastable nano-particles with small positive forming enthalpy and the real Zc of the alloy could be less than 1 mm predicted by parameter gamma.